The autartec project, funded by the German Federal Ministry of Education and Research under grant 03WKCH03C, ran from 1 September 2014 to 31 January 2018. Its core objective was to develop function‑bearing building bodies that integrate energy storage, solar heating, photovoltaic generation and adiabatic cooling into a floating architecture. The consortium, led by Wilde Metallbau GmbH, included partners such as IVI, AIB, INNIUS and other specialists in textile concrete, sandwich structures and marine systems. The project’s milestones covered design, testing, logistics, anchoring, and the final commissioning of a technology demonstrator on the Bergheider See.

Technically, the project focused on a coupling pontoon system that could be assembled from prefabricated modules. Four design variants were evaluated: a “Floss” (stringer) configuration, a closed “Topf” (pot) design, an open “Topf” with pneumatic control, and a rectangular “Quader” layout. All variants used polyethylene (PE) as the primary buoyant material, with options for glass‑fibre reinforced plastic (GFRP), steel, or composite concrete. The PE material was chosen for its excellent corrosion resistance, UV protection and lack of required conservation measures. Structural frames were designed to transfer loads from the buoyant cores to the hull and to the anchoring system. In the “Floss” and “Quader” variants, a rigid, bending‑stiffened frame or plate was placed above the cylinders, ensuring that the buoyant cores remained statically load‑connected. The open “Topf” variant incorporated a pneumatic trim system that actively regulated water level in the cores, allowing for active ballast control. Passive trim was achieved in the other variants by adding ballast weight.

The design process also addressed ice formation and pressure. Ice buildup inside the cores could impede active trim and increase radial stresses. Consequently, the “Quader” design incorporated additional stiffening ribs and a thicker wall to resist ice pressure, while the open “Topf” variant used a pressure‑release system to mitigate ice accumulation. The maximum dimensions of the buoyant cores were 12 000 mm in length, 2 500 mm in width and 3 000 mm in height, allowing for a substantial internal volume for energy storage and living spaces.

Performance testing was carried out under realistic loading conditions. The buoyancy tests confirmed that the pontoon system met the required displacement and stability criteria. The lift‑traverse system, a key component for modular assembly, achieved the target lift capacity and travel speed within the scheduled milestones. The integration of the WAE‑VS (water‑based energy storage and ventilation system) was completed, demonstrating the feasibility of coupling thermal and electrical storage with the floating structure. The final demonstrator, completed in late 2016, showcased a fully operational floating building with integrated solar panels, heat‑storage tanks, and a modular pontoon platform.

Throughout the project, the partners coordinated design, fabrication, and installation activities. Wilde Metallbau led the structural design and fabrication of the pontoon modules, while IVI and AIB contributed to the architectural and mechanical integration. INNIUS handled the building services engineering, ensuring that the energy systems were seamlessly embedded into the structure. The project’s timeline was largely adhered to, with most milestones achieved on schedule, although some delays were noted due to the complexity of the anchoring system and the need for iterative design adjustments at the new site.

In summary, the autartec project delivered a validated, modular floating architecture platform that integrates buoyancy, structural integrity, and autonomous energy systems. The technical results demonstrate that polyethylene‑based pontoon cores, combined with rigid framing and active or passive trim mechanisms, can provide reliable buoyancy and structural performance while accommodating integrated energy storage. The collaborative effort among engineering, architectural, and energy specialists, supported by federal funding, has produced a demonstrator that advances the field of autonomous floating buildings.